The present invention relates to improvements in V/STOL type aircraft, having at least one principle, thrust producing propulsion engine, either constructed as pivot or swivel nozzle, and/or having additional lift engines. Moreover, the aircraft is presumed to have control nozzles for controlling the craft during takeoff, landing and during the respectively succeeding and preceding transition phases. These control nozzles bleed air from the/or an engine.
The amount of air which can be bled or tapped from one of the engines is quite limited. Usually, one can tap an engine only to the extent that the available flow through the control nozzles just suffices for normal and regular operation. An increase in that control flow is usually not possible.
The aforementioned limitation has, for example, as a consequence that an increased load, such as additional loads on the wings, cannot be accommodated. Any interfering moment on the roll axis in the hovering phase may no longer be compensated under such circumstances, or only after a significant delay. As this lagging response constitutes an immediate and present danger to the craft, steps must be taken to avoid it.
It has been suggested to avoid these difficulties by increasing the available control moment during the critical periods by heating the pressurized air in the control nozzles or to provide supplementary rocket engines. Both proposals suffer from the drawback that weight is added to the craft, as additional pipes, ignition apparatus, tanks etc. are required. Moreover, heating in particular introduces significant delay.